Pfizer says court invalidates Celebrex patent; plans to appeal

Pfizer said on Wednesday a court had invalidated a key patent behind its blockbuster Celebrex drug, and plans to appeal the judgement.

The company said in a news release that a federal court in Eastern Virginia had voided a reissue patent for celecoxib, the drug's active ingredient. A trial originally set for March 19 would have seen Pfizer square off against pharmaceutical rivals Teva Pharmaceuticals, Mylan Pharmaceuticals and Watson Laboratories, among others. The drug makers were looking to file a new application with the Food and Drug Administration for a generic form of celecoxib.

"Pfizer disagrees with the ruling and will pursue all available remedies, including an immediate appeal of the court's judgement," the company added.

The stock, which was halted on news pending, reopened to the downside. It fell 0.75 percent near $32.